题目内容
如图所示是倾角为45°的斜坡,在斜坡底端P点正上方某一位置Q处以速度v0水平向左抛出一个小球A,小球恰好能垂直落在斜坡上,运动时间为t1.小球B从同一点Q处自由下落,下落至P点的时间为t2.不计空气阻力,则t1∶t2
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954203479.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954203479.png)
A.1∶2 | B.1∶![]() | C.1∶3 | D.1∶![]() |
D
试题分析:A小球恰好能垂直落在斜坡上,如图所示,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250009542492907.jpg)
将小球的速度在水平和竖直方向正交分解,可知,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954265818.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954281496.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954327591.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954343773.png)
因此
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954359667.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954390621.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954421773.png)
这样
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250009544831209.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000954561619.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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A.1∶2 | B.1∶![]() | C.1∶3 | D.1∶![]() |